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The Classic Moat Problem


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6 replies to this topic

#1 BMAD

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Posted 17 July 2013 - 08:34 PM

this is a classic problem so i was surprised that i could not find it in the forum searches but of course that is not to say that it isn't there  :thumbsup: .

 

Problem:
 
Suppose you have two unit-length boards.  What is the widest moat you can cross if you have no means to nail or otherwise attach them together?

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#2 Joyandwarmfuzzies

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Posted 17 July 2013 - 09:14 PM

Spoiler for

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#3 Pickett

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Posted 18 July 2013 - 02:40 PM

Spoiler for

Spoiler for Really Crude Paint Job


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#4 plasmid

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Posted 18 July 2013 - 03:11 PM

With that setup, I don't think you can call the width of the moat equal to the hypotenuse of the triangle formed by half of the first board plus all of the second board. A line from one end of the first board to the end of the second board that's touching the opposite shore would not be perpendicular to the moat. You would need to solve for the length that's perpendicular to the moat in order to find out how wide of a moat you could cross.


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#5 James33

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Posted 18 July 2013 - 03:14 PM

What shape is the moat? Does it have to be a straight line? Can it vary in width?

 

If it can be any shape, just choose a moat in the shape of a very pointy arrow and cross over at the point using 1 board.


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#6 BMAD

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Posted 18 July 2013 - 03:59 PM

What shape is the moat? Does it have to be a straight line? Can it vary in width?

 

If it can be any shape, just choose a moat in the shape of a very pointy arrow and cross over at the point using 1 board.

 

What shape is the moat? Does it have to be a straight line? Can it vary in width?

 

If it can be any shape, just choose a moat in the shape of a very pointy arrow and cross over at the point using 1 board.

 

What shape is the moat? Does it have to be a straight line? Can it vary in width?

 

If it can be any shape, just choose a moat in the shape of a very pointy arrow and cross over at the point using 1 board.

The question isn't whether you CAN cross the moat.  The question is, what is the widest the moat can be to make it across.


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#7 bonanova

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Posted 18 July 2013 - 06:19 PM

Rookie's classic version (with some assumptions not made in the OP).

 

Spoiler for For those assumptions


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The greatest challenge to any thinker is stating the problem in a way that will allow a solution.
- Bertrand Russell




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